P8-P9-P10-Forces And Motion Flashcards
What is distance
How far an object has travelled and does not include direction
What is displacement?
Displacement includes distance and how the object moves.Measured in straight line from finish to end.Direction of straight line.
What does quantity equal
Quanit=measurement eg:weight
How to calculate magnitude
Magnitude=size/strength
What is scalars
Scalars-physical quantities that have size but no direction
What is vectors
Vectors-have size and direction and are physical quantities
What is distance and displacement scalar or vector
Distance is a scalar quantity to show how much distance an object has travelled while displacement is a vector of how far an object is out of place
What is velocity
A speed in given direction it is also vector.
What is a force in terms of scalars or vectors
Force is a vector as it always acts in one direction
How do you work out speed
Speed=distance/time
Scalar as its showing no direction
How to work out velocity
Velocity=displacement/time
Vector
Calculation to work out force
Force=mass x acceleration
Vector and is measured in (n)
What does a force do?
A force can make an object change shape,make it to start to move and make it slower or faster
Contact forces examples
Friction,air resistance,streching,tension
Non contact forces
Magnetic field,gravitational force,electrostatic force
Newtons third law
When two objects interact with eachother they exert equal and opposite forces on eachother.eg:standing on floor
Newtons second law
In order to make an object move from rest,the forces must be unequal.eg:pushing something
What is resultant force
A single force that represents the sum of forces that acts on a body
What is a moment
Turning effect of a force
How to get moment?
Moment,M=Force x perpendicular distance
What is the moment increased by
Increasing size of the force,using a spanner with a longer handle
What is a lever
A lever is a simple machine that makes work easier to do.for example scissors or opening a door
What do levers act as
As a force which multiplies which means they reduce the force needed to perform tasks
Moment for gears formula
Moment=turning force x gear radius
What happens when the output when it has lower speed
When the speed is lower it provides a higher turning force known as ‘low gear’.When it says high turning force it means gear is easier to turn
What happens when the output is at a high speed
When output is at a high speed it provides a low turning force effect/movement known as ‘high gear’.Also when it says low turning force it means opposite and its actually harder
What is the centre of gravity
the single point that its entire mass/weight is considered to be acting
Low density-high density
Float,sink
it is possible for a satellite to have a constant speed but a changing velocity
Yes as it could be changing direction therefore staying st the same speed but changing velocity.
Two forces of 15 N and 36 N are acting on a body. Calculate the possible
resultant forces and directions when the forces are acting:
36+15=51n
In opposite directions
36-15=21n
At a right angle
Square root 21^2+15^2=12 root 10=37.9°
Freely suspended
The object has gone back to its equilibrium position after the turning force has been taken.
What is mass
The amount of stuff in an object
List Some vector quantities
Force,velocity,displacement,acceleration,momentum
List some scalar
Speed,distance,mass,temperature,time
What is a contact force
A force in which when 2 objects are touching
What is a non contact force
A force that do not need to be touching for it to act
Effects of gravity
Makes things fall to ground,gives weight
How to calculate weight
Weight=mass x gravitation field strength
What happens when a force moves an object
When a force moves an object through a distance energy is transffered and work is done.
What are the energy stores energy is transferred when work is done?
When energy is transferred to the kinetic energy store of the object because it starts to moving but some is also being transferred to thermal energy stores.
How to calcukate work done
Work done=force times distance
Gravity
All matter has a gravitational field and attracts all other matter
The larger the mass,the stronger the field the greater the attraction
What is weight
The force exerted on a mass by the gravitational field in newtons
Whats earths gravitational field strength
G=9.8
Where does the weight of an object act
The centre of mass
If connected to a gear with fewer teeth
The second gear will turn faster,with less force,lower turning force
If connected to a gear with more teeth
Turns slower,more force,higher turning force
Newtons first law
An object at rest remains at rest, or if in motion, remains in motion at a constant velocity unless acted on by a net external force.
What increases thinking distance
Speed,affected by reaction time,concentration,tiredness,distractions,influence of drugs/alcohol
Conditions that increase braking distance
Speed,poor road conditions,bald tiess,worn brake pads,weight
How to calculate stopping distance
Stopping distance=thinking+braking distances
What is a force
A PUSH OR PULL, THAT ACTS ON AN OBJECT, DUE TO ITS INTERACTION WITH ANOTHER OBJECT
What is centre of mass?
This is the point in an object where its mass is evenly distributed. It is the average position of all the mass in the object.
How can we make an object stable?
An object will be nice and stable if it has low centre of gravity and wide base area
If an objects line of gravity is out of its base area what happens.
When an objects line of gravity is out of its base area this causes it to topple over.
Difference between centre of mass and gravity
The center of mass is about how mass is spread out; the center of gravity is about where weight acts due to gravity.
Define inertia
Tendency of an object to continue in a state of rest or uniform motion.(same speed and direction).
List the factors acting on a car at a steady speed
Gravity will be pulling the force down,air resistance will be working against the car,weight from the weight of the car,there will be thrust from the engine moving it forward and there will be a frictional force between the car and the road
Definition of proportional
Proportional means that two quantities increase or decrease in a consistent, predictable way. If one quantity changes, the other changes in the same ratio.
Definition of inversley proportional
Two quantites are inconsistent and as one increases the other decreases.As one changes the other changes in a different matter
Define inertial mass
How difficult it is to change an objects velocity.Defined as the ratio over accelerwtion
What is normal force
Normal force is the force exerted by a surface to support the weight of an object resting on it.
How to calculate thinking distance
Reaction time x breaking distance
How to calculate momentum
Mass x velocity
SUVAT
S-Displacement(distance)
U-intial velocity
V-final velocity
A=acceleration
T-time
What distance measurement is used when calculating a moment?
The perpendicular distance from the pivot to the line of action of the force.
How can a lever be used as a force multiplier?
If the distance between the effort and pivot is greater than the distance between the pivot and load, the force applied on the load is greater than the effort force. This is since the moment on both the effort and load must be the same.
What is the line of action
the line of action is simply the direction along which a force acts on an object, and it helps us understand how that force will influence the object’s movement.
How to calculate final velocity using time
V=U+(AxT)
Modern cars can have six gears. Explain why this is necessary.
to adjust speed and torque for different driving conditions. Lower gears provide more torque, which is useful for acceleration and climbing, while higher gears allow the car to move at faster speeds with less fuel consumption.
Explain why a bicycle can be thought of as a ‘distance multiplier’.
As a small force is put on the pedals which causes a large turning force within the wheels,moving the bike forward.
Use the equation W = F × d to explain how each of the following works without
either of them contravening the principle of conservation of energy. force multipliers
In a force multiplier, the same amount of work is done, but a smaller force is applied over a larger distance. This results in a larger output force over a shorter distance, following the principle of conservation of energy.”
Define conservation of energy
energy cannot be created or destroyed, but it can only change form
How to calculate acceleration
Final velocity-initial divided by Time
What is terminal velocity
When all forces are balanced so the speed becomes constant
What is rhe use of gears
Gears are used to change the moment of a turning effect
How do you increase speed using gears
Use a higher gear
What does rhe gear ratio show
How many times one gear has to rotate for another gear to rotate
How do you find centre of mass in a regular object
Draw all lines of symetry and find the point where all the lines meet
How do you find centre of mass in an irregular object
1-suspend the irregular object freely in the air with a plum line connected to the same point.
2-Draw a line where the plum line passes at the centre of mass lies somewhere on this line,exactly below the point where the object is hung.
3-rotate object and draw another line where the plum line passes.The point where the two lines meet is the centre of mass
What is the principle of moments and how is it worked out
This states that,for an object that is not turning:
The sum of all the clockwise moments about any point=the sum of all the anti clockwise moments sbout thay point
How to calculate parrolelogram of forces
Step 1:work out scale
Step 2:copy out one force-the length needs to be drawn to scale
Step 3:measure the angle
Step 4:draw the next force
Step 5:set compass to the size of one of the forces
Step 6:place compass point at the end of the other force and draw a arc
Step 7:set your compass to the size of the other force
Step 8:place compass at the end of the other force and draw an arc
Step 9:draw the resultsnt force from which the two arcs cross.
Step 10:using a ruler measure diagnol force
Step 11:calculate size of the resultant force
How do you find the vertical and horizontal components of a diagonal force?
Create a scale
Measure the angle of the line and then the line to scale
Draw a horizontal and vertical line meeting at the bottom of the arrow
Draw a dotted line horizontally and vertically from the end of the arrow,90°c to the horizontal and vertical lines
Measure how long each line is
Calculate the force of the horizontal and vertical componanrs using the scale
Definition of friction
Friction is the force exerted by a surface as an object move across it
How to calculate gear ratio
Number of teeth on the driven/number of teeth on the driver
How can we work out the size of the frictional force to maintain equillibrium
First we can draw a geometric ‘scaled’ freebody diagram with our weight acting straightdown to ground.
• Draw the force acting normal to the slop and the force acting along side/ parallel to the slope to form parallelogram.
• Measuring FN and FH will give use theirmagnitude and we can also get their angle easilv.
What is upthrust
A force that pushes something upwards
How do you work out distance
Distance=velocity x time
What is a scale diagram
A scale diagram is a drawing where distances and sizes are proportional to actual values, but reduced or enlarged by a specific ratio, or scale.
How to get final velocity
V^2=u^2+2as
What are non parralel forces
Non-parallel forces are forces that act at different angles to each other rather than in the same or directly opposite directions.
How to calculate resultant force
Mass times acceleration
Resultant force is measured in newtons
How to calculate friction
Friction=mass times acceleration
Suvat distance
S=1/2(u+v)xtime
How to calculate mass
Density x volume =mass
How to calculate density
Mass/volume
How to calculate volume
Mass/density
Define hooks law
The extension of a spring is directly proportional to the force applied, provided its limit of proportionality is not exceeded
Define spring constant
Spring Constant: A measure of a spring’s stiffness, which is the constant of proportionality for a spring’s extension. The higher the spring constant, the smaller the extension is for a given force.
What is the conservation of momentum
The total momentum of a system before an event is always equal to the total momentum of the system after the event
What is an elastic limit
The force beyond which an object will no longer deform elastically, and will instead deform inelastically.
What is Elastic Potential Energy
The energy stored in a spring when it is stretched or compressed, due to the work done on the spring by the deforming force. It is equal to the work done as long as the object does not plastically deform.
Force in a spring equation
Spring constant x extension
In a velocity time graph how do you calculate displacement
Area
How to find inertial mass
Ratio of force to acceleration for a object
How to calculate rate of change of momentum
mass x change in velocity/time
How do crumple zones affect a crash
They increase the time taken to change the momentum of the driver and passengers in a crash.This is through the material at the front of the car Which crumples easy absorbing the contact and dissipates the energy of the crash
How do seat belts effect a crash
They are designed to stretch a bit in a collision. This increases the time taken for the body’s momentum to reach zero, and so reduces the forces on it.
How do air bags effect a crash
The air bag reduces the change in velocity by reducing the time it takes the passenger to stop moving. The air bag reduces the impulse by reducing the change in the passengers momentum
What is elastic deformation
Elastic deformation happens when a material is stretched or compressed but returns to its original shape when the force is removed.
What causes elastic and inelastic deformation?
Elastic deformation happens when the material is within its elastic limit. If too much force is applied, it goes past this limit and undergoes inelastic deformation, causing permanent damage
What are proportional,force ,extension or spring constant
Force is proportional to the extension
What happens when a force streches or compresses an object
Work is done and this causes energy to be transferred to the elastic potential energy store of an object.
How to calculate elastic potential energy
Elastic potential energy=1/2 x spring constant x extension^2
Steps to investigate the link between force and extension
Set Up the Apparatus – Attach a spring to a clamp stand and position a ruler alongside it to measure extension.
Measure the Initial Length – Record the spring’s length with no force applied.
Add a Mass – Hang a 100g mass (which applies 1N force due to gravity) and measure the new length.
Calculate Extension – Find the extension by subtracting the original length from the new length.
Repeat – Add more masses one at a time, recording the total force and the extension each time.
Plot a Graph – Plot force (N) on the y-axis and extension (cm or m) on the x-axis.
Analyse the Results – If the spring follows Hooke’s Law, the graph should show a straight-line relationship until the elastic limit.
What equipment do you need to investigate link between forces and extension
Clamp stand
Boss and clamp
Spring
Metre ruler
Masses (e.g., 100g )
How to calculate distance travelled in a velocity time graph
Velocity x time
What is uniform acceleration
Speeding up or slowing down at a constant rate
Define acceleration
Change in velocity in a certain amount of time
What is decelaetion
Negative acceleration,slowing down
Features of a distance time graph
Gradient=speed,steeper the graph the faster the object is going.
Flat sections is where its stationary
Straight uphill sections means its at a steady speed
Curves represents acceleration and deceleration
A steepening curve means its speeding up,levelling curve means its slowing down
Features of a velocity time graph
Gradient=acceleration,
Flat sections represents travelling at a steady speed
The steeper the graph the greater the accelerwtion/deceleration
Uphill sections are acceleration
Downhill sections are decleration
Curves means changing acceleration
The area under any section of rhe graph is equal to distance travelled
What is drag
The resistance you get in a fluid
What is air resistance
A type of drag
When an objects falls through fluids it reaches terminal velocity.How does it do this?
When an object falling first sets off the force of gravity is much more than the frictional forces slowing it down so it accelerates.As the speed increases the friction builds up.This gradually reduces the accelerwtion until eventually the frictional force is equal to the accelerating force.Reaching terminal velocity
How to investigate motion
Look at photo
What are reaction times affected by
Tiredness,drugs,alcohol,distractions
What happens if a moving car hits the back of a parked car?
The crash causes the two cars to lock together and they continue moving in the direction that the original moving car was travelling but at a lower velocity
What happens if a momentum is changed very quickly
It will have a larger impact and for example with a car it will cause a larger damage
How do crash mats help with crashes
They increase the time taken for you to sop it you fall on them.This is because they are made of soft,compressible materials
Equaion To calculate displacement
S=u x t + 1/2xaxt^2
If something starts from rest what will the intial velocity be
0
If something is stopping what will the final velocity be
0
Objects falling how fast if they are constant
A=9.8m/s^2
How to prove newtons 2nd law
Accelerate trolley on track with slotted mass on string over pulley.
- Use light/photogates to measure acceleration.
- Change force by removing masses and placing on trolley (to keep the total mass the same).
- Plot F against a, gradient = total mass.
How to calculate kinetic energy
1/2 x mass x velocity^2
Unit for momentum
Kgm/s
When does rebound occur
Rebound occurs when an object bounces back after hitting another surface or object.
Equation for rebound
M1u1 + m2u2=m1v1+m2v2
What is coupling in terms of momentum
Coupling happens when two objects collide and stick together, moving as one combined mass after the collision.
Equation for coupling
M1u1+m2u2=(m1+m2)x v
When does recoil happen
Recoil happens when an object moves backward after applying force in the opposite direction.
Equation for recoil
M1v1=-m2v2
What is force a measure of
The rate of change of momentum
How to calculate spring constant
Force/extension
How to calculate decleration
F=mxa
Rearrange to
A=F/M
Main three types of forces
Push,pull or twist
What is an interaction pair
Forces that are equal in size and opposite in direction
When do we notice a gravatational force
When one of the masses is very big
What does resolving a force mean
Splitting a force into its horizontal and vertical components
Control variables in measuring the relationship between force and extension for a spring
Use the same spring throughout the experiment
What happens when a smaller gear drives a larger gear
Small gear:rotates faster,anticlockwise,smaller moment
Large output gear:Rotates slow,clockwise,larger moment
What happens when a larger gear drives a smaller gear
Larger driving gear:rotates slower,anticlockwise,large input moment
Smaller output gear:rotates faster,clockwise,smaller moment produced
Define equilibrium
An object is in equilibrium if the resultant force and resultant moment are both equal to zero.
What is plastic deformation
Permanent deformation which means the object will no longer return to its original shape when the deforming forces are removed.
How someone can check if the position found for the centre of mass is accurate
Balance its centre of mass on am object or a finger and if it remains balanced.You have found the centre of mass
What can extension be replaced with in the equation for spring force
Compression
Define extension
Increase in length of a spring when it is stretched
Unit for spring constant
N/m
